With gradual development of the digital imaging technology, digital imaging products, such as digital cameras and digital video cameras, are more and more widely used in the people's life, and the digital imaging products include more and more pixels. At present, in most digital products adopting high-pixel camera modules (wherein, a high-pixel camera means a camera including more than two million pixels), the positions of the lenses in the digital camera modules can to be regulated by lens actuators, so that the purposes of automatically focusing and improving the quality of photos or videos are realized. On the other hand, since these high-pixel camera modules are more and more widely used in digital products, the requirement for corresponding lens actuators is continuously enhanced. In the process of mass-production of lens actuators, a rapid and comprehensive method for inspecting the lens actuators and controlling their quality is required. In a comprehensive inspection process for a lens actuator, besides the control relationship between the lens actuator and a lens stroke (i.e., a relative distance between a lens and an image sensor), the inspection items should further include the tilt amplitude inspection for the lens actuator. The reason for which is that: if the tilt amplitude of a lens is too large, though a central portion of an image shot by the lens is focused, a peripheral portion of the image may be out of focus, and the quality of the image may be adversely affected. Furthermore, in numerous lens actuators, a kind of tilt-type optical image stabilization (OIS) voice coil motor (VCM) (for example, US Published Patent Application 20090237517 and CN Patent 200810090504.1) can deliberately change the tilt amplitude of a lens to realize the OIS effect. In this kind of lens actuator, the tilt amplitude of the lens directly affects the OIS effect, and thus the tilt amplitude of the lens becomes more important.
In the prior art, a conventional method for comprehensively inspecting a lens actuator includes: placing a dummy lens into the lens actuator, and measuring the stroke and the tilt amplitude of the dummy lens by different methods. For example, a distance sensor is used to measure the position of the top of the dummy lens from the above of the dummy lens and thereby calculate the stroke of the dummy lens; a reflective film is plated onto the bottom of the dummy lens, laser is transmitted to the reflective film, and the tilt amplitude of the dummy lens is calculated according to the position of reflected laser.
In the conventional inspection method, the dummy lens needs to be inserted into the lens actuator before the lens actuator inspection and removed from the lens actuator after the lens actuator inspection. These operations may cause the following problems:
1. Inserting and removing the dummy lens require additional tools, labor, and time, which increases not only the inspection cost but also the operating cost, and thus the production speed of the lens actuator is reduced;
2. The lens actuator and the dummy lens may be worn when inserting and removing the dummy lens; thus, the production defect rate of the lens actuator may increase, and the inspection cost and the operating cost may indirectly increase;
3. Since the wear of the lens actuator generated in the inspection process may cause that contaminants may be hidden in the lens actuator, when the lens actuator is assembled to a camera module, the hidden contaminants may fall to an image sensor of the camera module; thus, the quality of images shot by the camera module may be adversely affected, and the defect rate of the camera module may increase.